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Plant Growth-Promotion and IAA Secretion With Pseudomonas fluorescens and Pseudomonas putida

Amina Meliani, Ahmed Bensoltane, Loubna Benidire and Khalid Oufdou

The present study was undertaken to investigate the plant growth promoting traits of a PGPR P. fluorescens and P. putida like production of Indoleacetic Acid (IAA), siderophore and phosphate solubilization. Plant growth-promoting properties of the two isolates were undertaken for their ability to produce siderophore, indole acetic acid and phosphate solubilization activity. The Indole-3-acetic acid and several other tryptophan (Trp) derivatives were separated by HPLC and quantified according to their fluorescence. On the other hand and in function of the two different types of root response to Fe deficiency (strategies), the isolates were tested for their effect on seed germination, seedling growth of Lens culinaris (strategy II) and Hordeum vulgar (strategy I) under gnotobiotic conditions and for tryptophan (Trp)-dependent IAA production. Both P. fluorescens and P. putida were shown to produce 3-indole-acetic acid (IAA) in vitro, at concentrations of 89 µg.ml^-1 and 116 µg.ml^-1, respectively. Furthermore, high levels of IAA excreted by P. putida were most consistent in enhancing plant growth across the calculation of Vigor index. On a comparative basis P. fluorescens was most promising in promoting plant growth in the case of the plant of strategy I compared to plant of strategy II..